Flow Rate help: first tank

[gridley]

My wife and I are setting up our first tank. We have finished the plumbing and are ready to do a test fill with fresh water to check for leaks and to determine the appropriate water level. It has been suggested that I may not have enough water flow . . . so, in the desire to do this right, please advise . . .

My tank is 90G, and the sump, if compleltly full would hold 32G - a more realistic working volume would be closer to 23G (I think). My main drain is 1 1/2, I have a 1" emergancy drain, the return line is 3/4". My pump is a Laguna Max-Flow 600 (600gph). I realize that this is not a standard aquarium pump, but it is what came with the used system. Based on a recommendation I ran the following numbers through the Head Loss Calculator on Reef Central. The laguna pump is not listed on the Head Loss Calculator so I substatuted it with the Eheim 1060 which has a very similar gph rating. http://reefcentral.com/index.php/head-loss-calculator The vertical lenght is 4.25 feet; horizontal length is 1 foot; the pipe diameter is 3/4"; there are 4 90 degree elbows. This works out to 333 gph flow. It was suggested that I replumb the return line to 1". In that case the flow rate increases to 381 gph. However . . . The plumbing at the exit is a 3/4" fitting for the Lok-Line.

In addition I have two Hydor Koralia 2 powerheads at 600 gph and one Hydor Koralia 3 powerhead at 850 gph.

1. Do I have enough flow through the sump with the 3/4 line? (approx 33 gph)

2. Is there enough benefit to replumb and go with the 1" retrun line and gain approx 50gph of flow through the sump.

3. With the restriction to a 3/4" fitting for the Lok-Line, does that in effect create a 3/4" return line?

4. With the Hydor Powerheads (2050gph plus the retrun pump) do I have enough total water flow in the tank?

Thanks for the help.

[Myka]

Imo that return pump is insufficient. Ideal flow through a sump is 6.1 times per hour. This number is calculated to allowed 99% of the aquarium volume to pass through the sump every 24 hours. Since a protein skimmer can only process a certain amount of water, this 6x turnover provides the protein skimmer with an ideal amount of "old" water to filter. Keeping this in mind, the ideal turnover for a 90 gallon aquarium with about 20 gallons in the sump is about 670 gph (after head loss).

Is your return line drilled or does it run up over the edge of the tank? If it is drilled for a 3/4" bulkhead then increasing the plumbing without increasing the bulkhead would provide minimal improvement. Although with an appropriately sized return pump for a 90 gallon display, a 1" return line would be best. I would suggest you look at replacing the return pump. A Quiet One 4000 pump would be quite a good fit for your system, and is a popular pump at a reasonable price point. An Ocean Runner 3500 would be another good option although I find my Ocean Runner to have a slightly louder hum than my Quiet One pump.

As far as powerhead flow goes, it depends what kind of corals you want to keep. When calculating turnover, just use the volume of the display tank (don't include the sump). For softies and LPS I find 10-30 times turnover is ideal, and for SPS corals 50-100 times turnover is ideal.

[gridley]

Thank you very much -this is a huge help.

[gridley]

Hello Myka - As it is a slower day I just reread your reply and I wanted to say that I really appreciated your reply and the information that you have included. This has been a help as I try to figure out what steps to take.

My return line is plumbed through a bulkhead in the side of the tank and until I take things apart I do not know if there is room for a 1 inch buldhead to be put in the hole. One question that I still have relates to the lok-line that is attached to the return line. The lok-line I have has a 3/4 inch fitting - if I increase the pipe diameter to 1", and keep the current 3/4" lok-line fitting, am I gaining anything? I was looking at seveal sights for a 1" lok-line fitting and did not find any. Is there such a size? Are there other options?

Thanks

[Myka]

You're welcome.

It is unlikely that you could fit a 1" bulkhead in a hole that is drilled for a 3/4" bulkhead unless some weird size was drilled. That is just really unlikely. Since the tank is already drilled with a 3/4" bulkhead installed you may as well use it. One thing you can do is make sure that thin-walled PVC was used rather than thick-walled (SCH40) PVC. Using thin-walled PVC will give you a slightly larger internal diameter of the pipe and therefore allow a slightly higher flow. Just take the pipe size into account when figuring out head loss. I wouldn't change the 3/4" loc-line. You won't find 1" loc-line because it is not made.

[sphelps]

The 3/4"bulkhead won't make a difference. The head loss resulting from smaller pipe is from friction alone so that 50gph loss you're seeing is purely from the extra friction from the length of all the pipe and fittings. Increasing the pipe and fittings to 1"will still give you the same gain despite the bulkhead at the end staying at 3/4", this will only act as a nozzle increasing velocity but flow rate for the most part will be unaffected. I should add I agree the pump is a bit small, personally I like to run larger return flow rates to cut back on the need for supplemental from powerheads.

[Myka]

What Steve says is true, but I wouldn't bother changing the size of the pipe. It's already there, may as well use it. Unless it is plumbed weird. If it makes the difference between on size pump and the next size up then I would definitely change it.

[gridley]

Well, latest inteligence shows (while testing the plumbing) that I should not become a plumber. I have one joint leaking in that line . . . so, I quess that I will increase it to a 1" line and maintain the 3/4" bulkhead, which if I understand what is being said, will not signifianctly decrease the flow, but only increase the velocity. So, I will now get my brother in law plumber over to do it correctly.

Thanks to everyone for the help and advice on this seemingly never ending challenge of getting water into the tank.

[Madmak]

Originally Posted by gridley

Thanks to everyone for the help and advice on this seemingly never ending challenge of getting water into the tank.

Haven't we all said this a few times before...

[gridley]

Originally Posted by Madmak

Haven't we all said this a few times before...

I appreciate hearing that. I was getting discouraged over the weekend at how long this is taking.